1. Field of the Invention
The present invention relates to transmission of data in one or more channels between modules interconnected by physical communication links in a terminal.
2. Description of the Related Art
Telecommunication systems include terminal equipment that processes data at exceptionally high data-rates, since such processing generally occurs with a speed greater than the transmission rate of the signals received and transmitted through the terminal. Such equipment may be physically implemented with specialized circuit boards mounted in slots within racks that make up the terminal equipment frame. Circuit boards and racks are interconnected with data communication links (e.g., parallel data buses or serial data links) that are part of a back-plane that is common to some or all of the racks.
However, as inter-board and inter-rack data rates in high speed systems (e.g., networking switches and routers) continue to increase, it is increasingly desirable to include back-plane communication links that are inexpensive to implement while providing relatively high-quality communication performance. High quality may be measured in terms such as low bit error rate (BER) or high total data throughput. However, these two requirements are hard to meet at the same time. Due to these high speeds of data in the back-plane, multiple physical links are typically needed for the required bandwidth of the communication link, thus increasing the cost of implementing the communication links.
Different methods exist to implement high-speed back-planes. Parallel back-planes include 32-bit and 64-bit PCI buses. Serial interfaces include 8b/10b encoded data (e.g., FibreChannel and Ethernet) and scrambled data (e.g., pseudo-SONET implementations).
Serial interfaces such as FibreChannel, Ethernet, and pseudo-SONET were initially implemented as single-channel communication links, but some recent implementations use (“bond”) multiple single-channel links into a single high-bandwidth link. In order to transfer packet data across multiple, bonded links, two different implementations are employed in the prior art, both of which lead to very high cost of implementation. The first implementation concatenates all of the incoming data streams into a single data stream at a bit rate that is the incoming bit rate multiplied by the number of physical links bonded together. The second implementation performs packet delineation on each individual link independently, thus requiring as many packet framers as there are links. One cost associated with using multiple physical links with packet delineation is the cost added by a high-speed framer that must be associated with each link.